Method and apparatus for coating a moving web of paper or board

ABSTRACT

A method and apparatus for coating a moving web of paper or board from on sides with at least one coat layer. The coat is applied to the web by means of a film transfer coater ( 12 ) and next the web is passed to a dryer cylinder group ( 4 ) via an air-cushion cylinder ( 18 ) supported by a wire ( 14 ), whereby the web can run fully supported all the way from its entry to the coater up to the winder. The apparatus further comprises a belt calender ( 8 ) and a belt-supported winder ( 9 ), whereby the web is thus supported over its entire passage in the machinery from the unwinder or paper machine up to winding.

Method and apparatus for coating a moving web of paper or board

FIELD OF THE INVENTION

The present invention relates to a method and apparatus for two-sidedcoating of a moving paper or board web with at least one coat layer.

BACKGROUND OF THE INVENTION

In the coating of a paper web, to a base sheet manufactured in a papermachine is applied a coating mix layer that is smoothed to a desiredthickness. The coating mix is made by slurrying coat solids into waterand the web is dried after coat application prior to its entry into thesubsequent finishing steps. The coater machine can be placed eitherdirectly after the paper machine manufacturing the base sheet, wherebythe arrangement is called an on-line layout, or alternatively, as aseparate section to which the wound base sheet rolls are transported tobe unwound there and coated in an entirely separate off-line coater.

The production capacity of a coater machine is chiefly dictated by itswidth, web speed and reliability of the machine function. The mostimportant factor affecting the functional reliability is the number ofweb breaks that should be kept as small as possible. Today, papermachines and coaters are already very wide, up to about 8-10 m, and agreater width is extremely difficult to achieve due to a number ofreasons including the greater bowing of rolls. Hence, the productivityof paper machines and coaters is preferably improved by elevating theweb speeds in these machines. However, at higher web speeds also the webrun in the coater becomes more difficult to control. One major problemis caused by the boundary air layer travelling on the rapidly moving webthat tends to detach the web from its support rolls. If the web losesits contact with the support rolls, control of web run becomesimpossible and, respectively, loss of web contact with the backing rollat the applicator causes bagginess and problems in the application andsmoothing of the applied coat. Hence, the control of web run in fastcoating machines must be accomplished by means different from those usedin prior-art machines. The most common technique is to use an at leastpartially supported web run through the machine. When the web is passedsupported by an air-permeable wire or belt, the formation of an airlayer between the web and the support wire or belt is prevented, thusallowing the web to stay in intimate contact with the surface of thesupport means. Further, a supported web run is an effective measure toreduce the number of web breaks due to variations in web tension,because tensioning of the web itself is not needed.

Instead of a wire, an air-cushion-type support means can be used in acoater for guiding the web run after coating, thus avoiding physicalcontact of any mechanical elements with the web. However, theair-cushion supported web guidance requires a substantially bulky freespace particularly in the vertical dimensions of the machine, becausethe web cannot be guided by an air-cushion turning means insubstantially sharp bends, particularly not through a sequence of sharpbends. Air-cushion-supported web run also needs dedicated means forthreading the web trailing end through air dryers and air-cushionturning devices, because air dryers and air-cushion turning devices areincapable of pulling the web forward, but rather, the web must be drawnthrough the dryer units by means of pulling roll group or similarpulling means located after the dryer section and capable of maintaininga sufficiently tight web draw. However, this arrangement also involvesthe risk of web breaks due to variations in web tension.

In the manufacture of a coated paper grades, the current trend is to usea base sheet as thin as possible because the quality of the finishedpaper can be improved by coating in a better manner than by increasingthe thickness of the base sheet and, moreover, the cost of the coat isappreciably lower than that of the base sheet. Obviously, the strengthof a thinner base sheet is much lower and, hence, the risk of web breaksparticularly when the base sheet becomes wet in application of thecoating will be greater the thinner the base sheet that is used. Hence,the choice of a suitable application method is a particularly vitalquestion in machines running at high web speeds and making thin papergrades. The optimal coating techniques for fast machines are suchapplications methods as film transfer application, jet application andspray application which impose a minimal stress on the web and cause aminimum penetration of coating mix and moisture into the web.Particularly advantageous herein is that these application methods atbest can apply only so much coat to the web that no doctoring afterapplication is required. Obviously, the stress of application on the webis thus minimized. When this kind of an application method causing aminimum stress on the web is combined with, e.g., an entirely belt- andwire-supported web run through the entire machine, the system can bemade to operate extremely reliably even at high web speeds.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method capable ofpermitting a substantial speed increase of a paper web coating machine,yet simultaneously keeping the vertical and machine-direction spacerequirements of the machine within reasonable dimensions.

The goal of the invention is achieved by way of advantageously using afilm transfer coater for applying the coat to the web and then passingthe web to a dryer cylinder group over a wire-supported air-cushioncylinder, thus making it possible to support the web over its entire runfrom application to the end of drying.

According to a preferred embodiment of the invention, the apparatus alsoincludes a belt calender and a beltsupported winder, whereby the web isessentially supported over its entire run from the unwinder or papermachine exit end to the winder.

The invention offers significant benefits.

By virtue of the invention, the coater design can be made very compactand the web can be easily passed from the support elements of one papermachine section to the next. The web run is entirely supported exceptfor a short length at the web tension measurement equipment, thusallowing the frequency of web breaks to be reduced to a minimum. The webis coated in a film transfer coater and then passed to a first dryermember which is a cylinder with an air-cushion function. On theair-cushion cylinder, the web surface is dried by air ejected throughthe cylinder shell, while the web is simultaneously supported by thewire and guided by its edges resting against the cylinder rims. Usingbelt supported top-side film transfer coaters, the coat can be appliedto the upper surface of the web, whereby the length of web run isminimized. With the help of the air-cushion cylinder, the web can bepassed via a very uncomplicated path to the dryer cylinders withoutmarring the applied coat, yet keeping the length of web run at aminimum. The web is dried finally in a wire-supported dryer cylindersection and subsequently passed on the support belt of the next coatersection. Here, the other side of the web is coated by film transferapplicators and the web is passed over an air-cushion cylinder to thenext dryer cylinder section in the same manner as described above,whereby the construction and web run of the second coater/dryer sectionbecomes very uncomplicated, too. The equipment may be veryadvantageously combined with a belt-supported calender and abelt-supported winder, whereby the web will run fully supported all theway starting from its entry to the coater and ending at the winder.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, wherein like reference numerals delineate similarelements throughout the several views:

FIG. 1 shows schematically an embodiment of a coater according to theinvention;

FIG. 2 shows schematically the principle of web spreading by means ofthe wire width control;

FIG. 3 shows schematically one technique of wire width narrowing; and

FIG. 4 shows schematically another technique of wire width narrowing.

Other objects and features of the present invention will become apparentfrom the following detailed description considered in conjunction withthe accompanying drawings. It is to be understood, however, that thedrawings are intended solely for purposes of illustration and not as adefinition of the limits of the invention, for which reference should bemade to the appended claims.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

The coater machine shown in FIG. 6 comprises an on-machine applicator,whereby the paper web passed thereto is first introduced to anintervening calender 1, from which the web is passed forward in themachine.

In the machine, the web is first passed to a first film transfer coater2 in which the coat is applied to the top side of the web. From the filmtransfer coater 2, the coated web is passed over an air-cushion cylinder3 to a dryer cylinder section 4. From the dryer section 4, the web isfurther passed to the next film transfer coater 5 in which the bottomside of the web is coated. After the bottom side of the web is coated,the moist web is passed to a second air-cushion cylinder 6 and furtherto a second dryer cylinder section 7. The dried web is next passed ontoa first calender belt of a belt calender 8 and, supported thereon, intothe first calender nip, therefrom onto the second calender belt and intothe second calender nip. From the calender 8, the web is passed to abelt-supported winder 9.

The web is passed to the coater from a support belt 10 on which the webruns when it is passed to the support belt 11 of the first film transfercoater.

The first coater station 2 is a top-side film transfer coater in whichthe upper roll 12 of the coater acts as the applicator roll. The supportbelt 11 passes over a lower roll 13 which serves as the backing roll ofthe film transfer coater. In this manner, the web can be guidedmaximally smoothly from the intermediate calender or post-dryer sectionof the paper machine, or in an off-line coater machine, from theunwinder, to the film transfer coater and, therefrom, forward along amaximally straight path. From the support belt of the film transfercoater 2, the web runs unsupported over a short distance to the supportwire of the air-cushion cylinder. On the web passage from the supportbelt 11 of the film transfer coater to the support wire 14 of theair-cushion cylinder is adapted a scanning beam 15 of web tensionmeasurement equipment based on sensing with air-jet injection formeasuring the web tension and its tension profile, whereby these dataare used for controlling the draw between the film transfer coater andthe subsequent equipment. A draw-based web tension control scheme isnecessary because the web dimensions change with the variation of theweb moisture content during coat application. The web meets the supportwire of the air-cushion cylinder at a guide roll 17. Between this guideroll 17 and the air-cushion cylinder 18 is adapted a web spreadingdevice 16 as shown in more detail in FIG. 2.

Web elongation due to due to the wetting of the web at the coater may becompensated for by controlling the machine draws and web tension.However, the increase of web width must be compensated for by means ofseparate devices capable of spreading the web, thus keeping the websmoothly adhering to the support wires and belts. When the web is passedfrom the coater station to the support wire as in the exemplifyingembodiment illustrated in FIG. 1, web spreading can be implemented bynarrowing and spreading the support wire 14. This is accomplished bymeans of passing the web in the coater station from the support belt 11to the support wire at the wire-narrowing bowed roll, more exactly, byadapting the web to meet the support wire exactly at the wire-narrowingroll. The wire-narrowing roll 19 may be either a conventionalreverse-mounted spreading roll 19 of the type shown in FIG. 3 comprisedof roll segments mounted on a bowed shaft, or alternatively, a so-calledworm roll of the type shown in FIG. 4, whereby the contoured surface ofthe roll provides the wire-narrowing effect. At the wire-narrowing roll19, the wire width is narrowed due to the cross-machine elasticity ofthe wire, thus allowing the web to meet a narrowed support wire. Whenleaving the wire-narrowing roll, the wire tends to recover its normalwidth, whereby also the web is spread correspondingly. Next, the supportwire with the web travelling thereon can be passed to a conventionalstraight guide roll 20, after which a separate spreading roll 21 can beadditionally used if so required to compensate for web spreading. As themoisture content of the web is reduced in later sections, the web widthbecomes narrower thus causing the web to shrink with respect to wire,whereby no creasing or separation of the web from the support wire canoccur in the same manner as takes place with the increase of the webwidth.

In the support wire used for spreading the web, the available spreadingcapacity should be at least 0.5%, preferably greater than 1%, combinedwith a low elasticity. The wire should also offer a good adherence tothe web and the wire-narrowing roll, which means that the coefficient offriction on the wire surface should be high. If the wire is used as adryer wire, it must have good resistance to high temperatures and,further, the aerodynamic properties of the wire need to be good at highweb speeds. Obviously, the wire should be easily guidable, it may notcrease when passing over the wire-narrowing roll, and it should have asufficiently long service life. The meeting point of the web with thewire must be arranged to fall on the narrowed portion of the wire.

Subsequent to coating, the first dryer member in the layout according tothe invention is an air-cushion cylinder 18. This device comprises apressurized cylinder whose shell is perforated with holes through whichhot air or steam is injected outward and against which the running webis supported by the wire 14. The coated top side of the web faces theair-cushion cylinder, while the uncoated bottom side of the web issupported by the wire 14. With the help of the air jets injectedradially outward from the air-cushion cylinder 18, the web runsnoncontactingly over the surface of the air-cushion cylinder 18 and thusthe web is contactingly supported but for a short machine-directionlength by its edges that are pressed by the wire 14 against the enddeckles of the air-cushion cylinder 18.

As can be seen from FIG. 1, the web path from the film transfer coater 2to the air-cushion cylinder 18 is very short and straight. In a similarfashion, the web can also be passed to the next dryer member practicallyin the same horizontal plane as it approaches the air-cushion cylinder.Thus, the web meets and leaves the air-cushion cylinder in the samehorizontal level.

The web is passed from the wire of the air-cushion cylinder by means ofa pick-up roll 22 to the support wire 23 of the dryer cylinder group.The pick-up roll 22 is adapted to rest against the wire 14 of theair-cushion cylinder 18 and, respectively, against the wire 23 of thedryer cylinder group 4, and the web is passed from the wire 14 of theair-cushion cylinder 18 about the pick-up roll 22 to the wire 23 of thedryer cylinder group 4. The dryer cylinder group 4 includes the wire 23running over guide rolls 27, smooth web-contacting dryer cylinders 26,air-permeable air-impingement dryer cylinders 24 and high-velocity hoods25 adapted about said air-impingement dryer cylinders. The basic membersof the dryer group 4 are two air-impingement dryer cylinders 24 havingsmooth web-contacting dryer cylinders 26 adapted to their both sides.All the dryer cylinders are so located with regard to each other thatthe wire with the web supported by it will be wrapped by over 180° abouteach cylinder. After being partially dried at the air-cushion cylinder18, the web is next passed to the first smooth dryer cylinder 26, wherethe support wire presses the coated side of the web against the surfaceof the smooth dryer cylinder 26. Here, the hot cylinder evaporates themoisture of the web and its smooth surface partially smooths the surfaceof the coat adhering thereto. Next, the wire 23 and the web runningsupported by the same are passed to a first air-impingement dryercylinder 24 having high-velocity hoods 25 adapted there about. Theinterior of the hoods 25 is provided with a plurality of nozzles servingto blow a drying gas at a high velocity onto the web running on the wire23. Depending on the moisture content of the web and other factors, hotair or superheated steam may be used as the drying gas. The dryercylinder group comprises four smooth-surface dryer cylinders 26 and twolarger-diameter air-impingement dryer cylinders 25. The larger-diameterdryer cylinders are placed between the smooth dryer cylinders so thatthe web can be passed first to one smooth dryer cylinder, then to onelarge-diameter dryer cylinder 24 and further to a second smooth dryercylinder 26. The large-diameter dryer cylinders 24 may be either suctioncylinders, which are permeable to the drying gas and brought to avacuum, or alternatively, air-impingement dryer cylinders having asurface grooved so as to allow the drying gas impinging thereon toescape via the backside of the wire 23. The smooth surface cylinders aremounted in the same horizontal plane so that the height at which the webruns over these cylinders is located close to the web meeting/leavingpoint on the air-cushion cylinder surface, whereby the length of web runis reduced to the shortest possible distance and the coater spacerequirement in the vertical direction can be minimized.

After the web supported by the wire 23 of the dryer cylinder group 4 haspassed through the entire dryer cylinder section it is deliveredsupported by the wire 23 to the support belt 11 of the next coaterstation 5. Here, coat is applied to the other side of the web, that is,to the web bottom side which remained uncoated after leaving thepreceding coater station 2. Next, the support belt 11 of the coaterstation 5 runs about the upper roll of the film transfer coater, wherebysaid upper roll acts as the backing roll of the coater. Herefrom, theweb is passed to the dryer section of the line which is otherwisesimilar to that of the preceding coater section except for having thesupport wires and belts adapted to pass above the section members and,respectively, having the larger-diameter dryer cylinders 24 of thissecond dryer cylinder group 7 adapted below the smooth-surface dryercylinders 26. Also herein, the smooth dryer cylinders are placed in thesame horizontal plane and the meeting/leaving point of the web on theair-cushion cylinder is located in the vertical direction close to theplane in which the web runs over the smooth cylinders.

From the dryer group 7, the web is passed to a belt calender 8comprising two support belts and two calender nips. Each of the calendernips comprises one calender roll 28 with a cooperating backing roll 29.The calender belt 30 wraps about the backing roll, whereby the webpassed to the calender belt travels through the nip between the calenderroll 28 and the calender belt 29. In the first calender nip, thecalender roll is placed above the calender belt, and in the secondcalender nip, respectively, the calender roll is placed below thecalender belt 30. Thus, both sides of the sheet will be contacted withboth the calender roll and the calender belt during calendering. In asimilar manner as in all preceding sections, the web is passed from onenip to the next supported by the calender belts so that the web runtakes place supported along its entire length.

The winder 9 is of an entirely belt-supported type in which the web ispassed supported by a support belt 31 up to the paper/board roll 32. Thewinder comprises a winder cylinder 33 and a winder mandrel 34 forming anip through which the web is passed onto the mandrel. The winder furtherincludes a transfer device 35 for bringing a new mandrel into a nipcontact with the winder cylinder 33 when the paper or board roll woundabout the previous mandrel is full. The support belt 31 of the winder 9passes via the last nip formed by the calender belt 30 in calender 8 andthen travels to the winder cylinder 33. The change of the roll mandrel34 takes place by moving the guide roll 36 of the support belt 31 sothat the web is supported during the entire change-over operation by thesupport belt 31 and all the time passes through the nip between guideroll 36 and the paper/board roll 32. Simultaneously a new roll isbrought into contact with the web supported by the support belt 31 andthe web is severed so that it starts to wind up about the new rollmandrel 34. This type of winder is disclosed in FI laid-open publicationno. 94,231.

In addition to those described above, the invention may have alternativeembodiments.

The equipment layout described above is suited for two-sided coating ofa paper or board web with one coat layer on each side. Obviously, asimilar arrangement can be adapted to coaters in which both sides of theweb are coated with multiple layers of coating. Then, the coater must beprovided with the required number of coater and dryer units, eachcomprising an air-cushion cylinder and a dryer cylinder group. Thearrangement according to the invention can be used equally well as anon-line or an off-line coater.

In the above-described embodiment, the first coater station isconfigured as a top-side coater, while the latter is a bottom-sidecoater. Obviously, the order of the coater stations may be reversed andthe film transfer coater used therein may be replaced by othertechniques such as jet and spray applicators suitable for top-sidecoating. In the bottom-side coater station, also other coating methodsare applicable inasmuch a majority of conventional coater constructionsare designed for bottom-side coating from below the web. Obviously, thenumber of the dryer cylinders may be varied in such a manner that, e.g.,only one air-impingement dryer cylinder is used after each coaterstation or some of the coater stations. Also herein, a sufficient numberof web-contacting dryer cylinders are typically required, but where aparticularly low drying effect is desired, the web-contacting dryercylinders may even be omitted. In practice, the number of dryercylinders is determined by the needed drying effect.

Thus, while there have been shown and described and pointed outfundamental novel features of the present invention as applied to apreferred embodiment thereof, it will be understood that variousomissions and substitutions and changes in the form and details of thedevices illustrated, and in their operation, may be made by thoseskilled in the art without departing from the spirit of the presentinvention. For example, it is expressly intended that all combinationsof those elements and/or method steps which perform substantially thesame function in substantially the same way to achieve the same resultsare within the scope of the invention. Substitutions of elements fromone described embodiment to another are also fully intended andcontemplated. It is also to be understood that the drawings are notnecessarily drawn to scale but that they are merely conceptual innature. It is the intention, therefore, to be limited only as indicatedby the scope of the claims appended hereto.

What is claimed is:
 1. A method for coating a web of paper or boardcomprising: passing the web through a coater where a coat layer isapplied to a first side of the web, the web being supported by a belt inthe coater; passing the web from the coater through a first dryer wheremoisture is removed from the web, the first dryer comprising anair-cushion cylinder and a wire positioned to support a second side ofthe web so that the first side of the web faces the air-cushioncylinder; and passing the web from the first dryer through a seconddryer where moisture is removed from the web, the second dryercomprising at least one smooth-surfaced dryer cylinder, at least oneair-impingement dryer cylinder and a support wire, the wire beingpositioned to support the web so that the coated first side of the webwraps about a portion of a surface of the at least one smooth-surfaceddryer cylinder and so that the web wraps about a portion of a surface ofthe at least one air-impingement dryer cylinder, wherein drying gas isblown against the web as the web passes about the at least oneair-impingement dryer cylinder.
 2. The method of claim 1, furthercomprising contracting a width of the wire of the coater with awire-narrowing roll, wherein the web first contacts the wire of thefirst dryer at a point where the width of the wire is contracted so thatspreading of the wire downstream of the wire-narrowing roll to a naturalwidth of the wire also spreads the web.
 3. The method of claim 2,further comprising widening the width of the wire of the first dryerwith a wire-spreading roll positioned downstream of the wire-narrowingroll.
 4. The method of claim 1, further comprising measuring tension ofthe web as the web passes from belt of the coater to wire of the firstdryer, the web tension being measured by a web tension measurementdevice.
 5. The method of claim 4, wherein the web is supportedsubstantially at all times as it travels through the coater, the firstdryer and the second dryer, from the coater to the first dryer, and fromthe first dryer to the second dryer, except as the web passes by the webtension measurement device.
 6. The method of claim 1, wherein the weband the wire supporting the web through the first dryer wrap about aportion of the air-cushion cylinder so that the web initially faces theair-cushion cylinder in substantially the same horizontal plane as theweb leaves the air-cushion cylinder.
 7. The method of claim 1, whereinthe second dryer comprises at least two air-impingement dryer cylindersand at least two smooth-surfaced dryer cylinders, and wherein the atleast two smooth-surfaced dryer cylinders are positioned in a horizontalplane.
 8. The method of claim 1, wherein the second dryer comprises atleast two smooth-surfaced dryer cylinders positioned in a horizontalplane.
 9. The method of claim 1, wherein the web is passed from the wireof the first dryer to the support wire of the second dryer by a pick-upcylinder which contacts the wire of the first dryer and the support wireof the second dryer.
 10. The method of claim 1, further applying a coatlayer to a second side of web.
 11. The method of claim 1, furthercomprising applying another coat layer to the first side of the web. 12.The method of claim 10, further comprising applying another coat layerto the first and second sides of the web.
 13. The method of claim 10,further comprising drying the applied coat layers.
 14. The method ofclaim 13, further comprising, after drying the applied coat layers,transferring the web onto a first calendar belt through a first calendernip.
 15. The method of claim 14, further comprising transferring the webdownstream of the calender nip from the first calender belt to a secondcalender belt and passing the web on the second calender belt through asecond calender nip.
 16. The method of claim 15, further comprisingtransferring the web from the second calender belt downstream of thecalender nip to a support belt of a belt-supported winder.
 17. Themethod of claim 1, wherein the coater comprises a belt-supported filmtransfer coater.
 18. An apparatus for coating a web of paper or boardcomprising: a coater comprising a means for applying a coating layer toa first side of a web, and a belt for supporting the web and for passingthe web to and through the coater; a first dryer where moisture isremoved from the web, said first dryer comprising an air-cushioncylinder and a wire positioned to support a second side of the web sothat the first side of the web faces said air-cushion cylinder and toreceive the web from said belt of said coater; and a second dryer wheremoisture is removed from the web, said second dryer comprising at leastone smooth-surfaced dryer cylinder, at least one air-impingement dryercylinder, a support wire, and at least one hood, said wire of saidsecond dryer being positioned to receive the web from said wire of saidfirst dryer and to support the web so that the coated first side of theweb wraps about a portion of a surface of said at least onesmooth-surfaced dryer cylinder and so that the web wraps about a portionof a surface of said at least one airimpingement dryer cylinder so thatthe coated surface of the web is not in contact with the surface of saidat least one air-impingement dryer cylinder, said at least one hoodbeing positioned about said at least one air-impingement dryer cylinderfor blowing drying gas against the coated web surface as the web passesabout said at least one air-impingement dryer cylinder.
 19. Theapparatus of claim 18, wherein said first dryer futher comprises awire-narrowing roll positioned against said wire of said first dryer tocontract a width of said wire of said first dryer.
 20. The apparatus ofclaim 19, wherein said wire-narrowing roll comprises a reverse-mountedspreading roll having roll segments.
 21. The apparatus of claim 19,wherein said wire-narrowing roll comprises a grooved worm roll.
 22. Theapparatus of claim 19, wherein the web first contacts said wire of saidfirst dryer at a point where the width of said wire of said first dryeris contracted by said wire-narrowing roll so that spreading of said wireof said first dryer to its natural width downstream of said point alsospreads the web.
 23. The apparatus of claim 19, wherein said first dryercomprises a wire-spreading roll positioned downstream of saidwire-narrowing roll and against said wire of said first dryer to spreadthe width of said wire of said first dryer.
 24. The apparatus of claim23, wherein said wire-spreading roll comprises a spreading roll havingroll segments.
 25. The apparatus of claim 23, wherein saidwire-spreading roll comprises a worm roll.
 26. The apparatus of claim18, further comprising a web tension measuring device positioned tomeasure tension of the web as the web passes from said belt of saidcoater to said wire of said first dryer.
 27. The apparatus of claim 18,wherein the web and said wire of said first dryer wrap about a portionof the air-cushion cylinder so that the web initially faces saidair-cushion cylinder in substantially the same horizontal plane as theweb leaves said air-cushion cylinder.
 28. The apparatus of claim 18,wherein said second dryer comprises at least two air-impingement dryercylinders and at least two smooth-surfaced dryer cylinders, and whereinsaid at least two smooth-surfaced dryer cylinders are positioned in ahorizontal plane.
 29. The apparatus of claim 18, further comprising apick-up cylinder positioned to transfer the web from said wire of saidfirst dryer to said wire of said second dryer, said pick-up cylinderbeing positioned to contact said wire of said first dryer and said wireof said second dryer.
 30. The apparatus of claim 18, further comprisinga second coater to apply a coating layer to a second side of the web.31. The apparatus of claim 18, further comprising a second coater toapply another coating layer to the first side of the web.
 32. Theapparatus of claim 30, further comprising a plurality of coaters toapply another coating layer to the first and second sides of the web.33. The apparatus of claim 18, further comprising: a first calender nipfor calendering the web; and a first calender belt positioned to receivethe coated web and to pass the web supported by said first calender beltthrough said first calender nip.
 34. The apparatus of claim 30, furthercomprising: a first calender nip for calendering the web; and a firstcalender belt positioned to receive the coated web and to pass the websupported by said first calender belt through said first calender nip.35. The apparatus of claim 32, further comprising: a first calender nipfor calendering the web; and a first calender belt positioned to receivethe coated web and to pass the web supported by said first calender beltthrough said first calender nip.
 36. The apparatus of claim 335, furthercomprising: a second calender nip for calendering the web; and a secondcalender belt positioned to receive the web from the first calender beltand to pass the web supported by said second calender belt through saidsecond calender nip.
 37. The apparatus of claim 34, further comprising:a second calender nip for calendering the web; and a second calenderbelt positioned to receive the web from the first calender belt and topass the web supported by said second calender belt through said secondcalender nip.
 38. The apparatus of claim 35, further comprising: asecond calender nip for calendering the web; and a second calender beltpositioned to receive the web from the first calender belt and to passthe web supported by said second calender belt through said secondcalender nip.
 39. The apparatus of claim 36, further comprising abelt-supported winder comprising a belt positioned to receive the webfrom the second calender belt downstream of said second calender nip.40. The apparatus of claim 37, further comprising a belt-supportedwinder comprising a belt positioned to receive the web from the secondcalender belt downstream of said second calender nip.
 41. The apparatusof claim 38, further comprising a belt-supported winder comprising abelt positioned to receive the web from the second calender beltdownstream of said second calender nip.
 42. The apparatus of claim 18,wherein said coater is a film transfer coater.
 43. The apparatus ofclaim 18, wherein said air-cushion cylinder of said first dryer and saidat least one smooth-surfaced dryer cylinders of said second dryer arepositioned so that the web first contacts said air-cushion cylinder ofsaid first dryer in substantially the same horizontal plane as where theweb leaves a last of said at least one smooth-surfaced dryer cylindersof said second dryer.